GRK2, Active

GRK2 or ADRBK1 is a ubiquitous cytosolic enzyme that specifically phosphorylates the activated form of the beta-adrenergic and related G protein-coupled receptors. GRK2 phosphorylates the beta-2-adrenergic receptor and appears to mediate agonist-specific desensitization. Abnormal coupling of beta-adrenergic receptor to G protein is involved in the pathogenesis of the failing heart (1). RAF kinase inhibitor protein RKIP is a physiologic inhibitor of GRK2 (2). After stimulation of G protein-coupled receptors, RKIP dissociates from its known target, RAF1 to associate with GRK2 and block its activity.